This invention relates to apparatus and method for disposition of radioactive waste materials.
While the invention may be used for the packaging and disposition of various types of radioactive or chemically dangerous wastes, it can be exceptionally advantageously employed in the disposition of radioactive wastes as they occur in nuclear electric power generating stations.
In both boiling water and pressurized water reactors of nuclear power plants, it is a practice to subject the water to cleaning action by passing it through beds of ion-exchange resins. Through chemical and filtering action, they remove dissolved and suspended impurities, thus maintaining the water and at the desired high purity. Resin particles of one type widely used for this purpose are those approximately 20 mesh in size. Resin particles of another widely used type are much smaller, approximating 300 mesh in size.
The contaminated resins of either type are removed from the water treating vessel by sluicing them out with water. The resulting slurry or dispersion is collected in a waste resin tank at the plant. The apparatus disclosed hereafter is particularly well adapted for disposition of this type of radioactive slurry.
Stringent laws, rules and regulations govern the disposition of radioactive wastes and their transportation over highways, on railroad and by other modes of transportation. In general, the material must be shielded so that radiations emanating from the material do not exceed maximum levels established by the laws and regulations. It has therefore been proposed to provide a mixture of resin particles containing radioactive material, cement as a solidifying agent, and water in a container such as a steel drum, and to allow the mixture to solidify in the drum.
However, prior systems for putting radioactive materials into a drum or other container in general require that operators and maintenance personnel be exposed to radiation, even though such system may be intended to protect personnel. For example, the operators in many cases must go into areas containing radiation to open drums or close them or to insert nozzles in the drums or to handle the drums in storage.
Moreover, prior systems do not in general provide desired close control to insure that proper amount of radioactive material, cement, or water are put into the drum to insure proper solidification of drum contents. It is imperative to avoid improper loading of the drum or mixing of drum contents. Previous systems did not provide for an accurate weight of resin to a weight of cement ratio in order to insure that the drum contents would be properly solidified with the most economical use of cement and with the lowest transportation costs. In prior systems that filter the resin in the drums to remove water, costs are understandably higher for the drum because of the added equipment contained herein.
Some prior systems mix radioactive resins, cement and water in a mixture outside of a drum. This involves exposure of considerable amounts of equipment to radioactivity and possibilities of considerable exposure of personnel to radioactivity. Moreover, the mixer must be cleaned after each use, which is difficult because the cement sticks to the mixer; moreover, the mixer will become radioactive and hence unsafe in time considerably shorter than the life of the plant, necessitating replacement expense. Some prior systems mix these materials in the drum; but if an open top drum is used, considerable spillage occurs during mixing, and if the drum is rolled about its lengthwise axis to mix its contents a core of poorly mixed material is formed in the center of the drum.